Bidirectional sensor

ABSTRACT

A bidirectional sensor includes a rectangular housing mounted on a base plate. A hollow cylindrical guide tube extends between opposite end walls of the housing and slidably receives an operator therewithin. A coil spring seating between one end wall and the operator biases the operator toward the other end wall to actuated position wherein the operator engages a primer or closes an electrical circuit. Three equally spaced radial openings in the wall of the tube receive respective balls which seat in a circumferential arcuate groove of the operator to detent the operator against movement under the spring bias. The balls are constrained against movement outward of the openings by a cylindrical detent member which surrounds the operator and has a first cylindrical shoulder thereof seating the balls in the operator groove and a second cylindrical shoulder slidable along the guide tube. A pair of rods extend parallel to the guide tube axis and slidably mount rectangularly shaped seismic masses, each having spaced shoulders provided by a cutout in the mass. Respective springs bias the masses opposite each other and into engagement with a respective end wall of the housing. One shoulder of each mass engages the detent member, generally diametrically and axially opposite of the other shoulder, to locate the detent member in detent position. Should either mass move against its bias under an acceleration pulse of predetermined amplitude and time, the other shoulder will engage the detent member to move the detent member out of engagement with the one shoulder of the other mass and move the first shoulder of the detent member out of engagement with the balls to release the operator.

United States Ptent [191 Prachar Apr. H7, 1973 BHDCTHONAL SENSOR OtakarP. Prachar, Santa Barbara, Calif.

[73] Assignee: General I Motors Detroit, Mich.

22 Filed: Nov.11,1971

21 Appl.No.: 197,736

[75] Inventor:

Corporation,

[56] References Cited UNITED STATES PATENTS 2,351,607 6/1944 Grant, Jr.et a1. ..74/2

Primary ExaminerMilt0n Kaufman Att0rneyW. E. Finken et al.

[ 5 7] ABSTRACT A bidirectional sensor includes a rectangular housingmounted on a'base plate. A hollow cylindrical guide tube extends betweenopposite end walls of the hous ing and slidably receives an operatortherewithin. A

coil spring seating between one end wall and the operator biases theoperator toward the other end wall to actuated position wherein theoperator engages a primer or closes an electrical circuit. Three equallyspaced radial openings in the wall of the tube receive respective ballswhich seat in a circumferential arcuate groove of the operator to detentthe operator against movement under the spring bias. The balls areconstrained against movement outward of the openings by a cylindricaldetent member which surrounds the operator and has a first cylindricalshoulder thereof seating the balls in the operator groove and a secondcylindrical shoulder slidable along the guide tube. A pair of rodsextend parallel to the guide tube axis and slidably mount rectangularlyshaped seismic masses, each having spaced shoulders provided by a cutoutin the mass. Respective springs bias the masses opposite each other andinto engagement with a respective end wall of the housing. One shoulderof each mass engages the detent member, generally diametrically andaxially opposite of the other shoulder, to locate the detent member indetent position. Should either mass move against its bias under anacceleration pulse of predetermined amplitude and time, the othershoulder will engage the detent member to move the detent member out ofengagement with the one shoulder of the other mass and move the firstshoulder of the detent member out of engagement with the balls torelease the operator.

4 Claims,'2 Drawing Figures PATENTEDAFR 1 11915 is; 727, 575

ATTORNEY BIDIRECTIONAL SENSOR This invention relates generally tobidirectional sensors and more particularly to bidirectional sensors ofthe type including a pair of seismic masses which move linearly relativeto a detented operator and release the operator for movement to anactuated position upon movement of either mass under an accelerationpulse of predetermined amplitude and time.

One feature of this invention is that the seismic masses arerespectively mounted for linear movement in directions opposite eachother and are respectively biased against such movement, with movementof either mass against its bias releasing a detent for the operator.Another feature is that the masses collectively locate the detent indetent position and movement of either mass releases the detent. Afurther feature is that the masses move in directions generally parallelto the direction of movement of the operator and include spacedshoulders arranged in respective pairs, one pair coacting to positionthe detent in detent position and either of the other pair moving thedetent coaxial of the operator to released position upon movement of arespective mass relative to the detent. Yet another feature is that thespaced shoulders are provided by cutouts in the masses, the one pair ofshoulders engaging the detent axially and diametrically opposite of eachother to locate the detent in detent position.

These and other features of the sensor of this invention will be readilyapparent from the following specification and drawings wherein:

FIG. 1 is a sectional view ofa sensor according to this invention inunactuated condition; and

FIG. 2 is a view similar to FIG. 1 showing the sensor in actuatedcondition.

Referring now particularly to FIG. 1, a sensor according to thisinvention includes a rectangular base plate 12 provided with a pluralityof openings 14 for mounting on a structure subject to accelerationpulses. A housing designated generally 16 includes a pair of rectangularside walls 18 and a pair of rectangular end walls 20 and 22 which aresuitably secured to each other and to the plate 12. The major axes ofthe side walls 18 extend in the same direction as the major axis of theplate 12 while the major axes of the end walls 20 and 22 extendtransversely of the plate 12 and in the same direction as the minor axisof the latter. The lower wall of the housing 16 is provided by the plate12 and the upper wall thereof is provided by a plate, not shown, whichis suitably secured to the walls 18, 20 and 22. The end wall 22 includesa central circular boss 24 having an opening 26. A fitting 28 isreceived within the boss 24 and mounts a conventional primer or cap 30.

Inner end walls 32 seat against and are secured to the inner surface ofthe walls 20 and 22. A pair of circular pins or rods 34 extend parallelto each other and generally longitudinally of the housing 16 and havetheir ends respectively piloted in aligned pairs of circular openings 36of the walls 32. A hollow cylindrical guide tube 38 extends betweenaligned cylindrical openings 40 of walls 32 and opens at one end to theprimer through a fitting 42. The axis of the guide tube 38 is parallelto those of the rods 34.

A pair of generally rectangularly shaped seismic masses 44 arerespectively mounted on a rod 34. Each mass is also of rectangular crosssection. Each mass includes a central bore receiving a respective rod 34and including a counterbore 46. A coil compression spring 48 seatsbetween each wall 32 and the base of a counterbore 46 to thereby biasthe masses 44 in linear directions oppositely of each other and engagerespective end faces 50 of the masses with respective end walls 32 ofthe housing. Each mass additionally includes a rectangularly shapedcutout providing a first shoulder 52 and a second shoulder 54.

A cylindrical operator 56 is slidably received in the guide tube 38 andincludes a tapered radial wall 58 which terminates in a sharp-pointedend 60. When the operator moves from its unactuated position shown inFIG. 1 to its actuated position shown in FIG. 2, the wall 58 and thepointed end 60 are received within a complementary shaped opening 62 ofthe fitting 42 and the end 60 engages the primer 30 to explode theprimer for a purpose to be hereinafter described. The operator 56 isnormally biased to its actuated position shown in FIG. 2 by a coilcompression spring 64 which seats between one end wall 32 and a shoulder66 of the operator.

The guide tube 38 includes three equally circumferentially spacedopenings 68, each of which receives a respective ball 70. A cylindricaldetent member 72 surrounds the guide tube 38 and includes a first radialend wall 74 terminating in a cylindrical opening 76 spaced from theouter surface of the guide tube as shown. The member 72 further includesa second radial end wall 78 and an intermediate radial wall 80 having ashallow arcuate cross section groove 82.

When the sensor 10 is in unactuated position shown in FIG. 1, the ballsseat in the groove 82 and in an arcuate cross-section circumferentialgroove 84 of the operator 56 in order to detent the balls 70 againstradial movement and thereby detent the operator in its unactuatedposition against the action of the spring 64. The detent member 72 islocated in its detent position shown in FIG. 1 by the engagement of theshoulder 52 of one mass 44 with the first radial end wall 74 and thediametrically opposite and axially spaced engagement of the shoulder 52of the other mass 44 with the second end wall 78.

When the sensor 10 is subjected to an acceleration pulse ofpredetermined amplitude and time directed generally parallel to the axesof the rods 34 and the guide tube 38, one of the masses 44 will moveagainst the bias of its respective spring 48. FIG. 2 shows one of themasses 44 having received a pulse in one direction and thereby movingagainst the bias of its spring 48. When the mass moves through thedistance between shoulders 52 and 54, shoulder 54 engages the first endwall 74 of the detent member 72 to move the detent member slightly tothe left to released position wherein the groove 82 thereof is out ofengagement with the balls 70. The spring 64 and the groove 84 thereuponcam the balls 70 radially outwardly from engagement with the operator 56and the operator moves from its unactuated position shown in FIG. 1 toits actuated position shown in FIG. 2. As shown in FIG. 2, the balls 70may either move to the radial space between walls 74 and or moveoutwardly of the detent member 72.

Should the pulse be received in an opposite direction, the other of themasses 44 will function in a like manner to move the detent member fromits detent position of FIG. 1 to its released position of FIG. 2 torelease the operator.

The sensor of this invention is particularly intended for use in avehicle body occupant restraint system which includes a source ofpressure fluid, such as a pressure vessel sealed by a rupturablediaphragm, for inflation of an inflatable occupant restraint cushionwhen the vehicle body receives a pulse of predetermined amplitude andtime. The sensor 10 will be mounted on the body in a manner to receivesuch pulse. The explosion of the primer 30 may directly rupture thediaphragm of the pressure vessel or actuate a primer cord to effect suchrupture. Likewise the operator 58 may close an electrical switch toeffect electric detonation and subsequent rupture of the diaphragm ormay directly rupture such diaphragm itself.

Thus, this invention provides an improved bidirectional sensor.

lclaim:

l. A bidirectional sensor comprising, in combination, a support, anoperator mounted on the support for movement between unactuated andactuated positions, means biasing the operator to actuated position,detent means movable between detent and released positions with respectto the operator and holding the operator against movement to actuatedposition in the detent position thereof, a pair of seismic masses, meansrespectively mounting each mass on the support for linear movementrelative to the detent means, means respectively biasing the masses inopposite linear directions to respective first positions and resistingreverse linear movement thereof to respective second positions uponreceipt thereby of an acceleration pulse of predetermined amplitude andtime directed generally linearly thereof, coacting means on each massand the detent means locating the detent means in detent position in thefirst position of the masses, and coacting means on each mass and thedetent means engageable with each other upon movement of either mass tothe second position thereof to move the detent means to releasedposition and permit movement of the operator to actuated position.

2. A bidirectional sensor comprising, in combination, a support, anoperator mounted on the support for axial movement between unactuatedand actuated positions, means biasing the operator to actuated position,detent means movable axially of the operator between detent and releasedpositions with respect thereto and holding the operator against movementto actuated position in the detent position thereof, a pair of seismicmasses, means respectively mounting each mass on the support formovement axially of the detent means, means respectively biasing themasses in opposite axial directions to respective first positions andresisting reverse axial movement thereof to respective second positionsupon receipt thereby of an acceleration pulse of predetermined amplitudeand time directed generally axially thereof, coacting means on each massand the detent means locating the detent means in detent position in thefirst position of the masses, and

second means on each mass spaced axially of the first means and thedetent means and engageable with the detent means upon movement ofeither mass to the second osition thereof to move the detent means torelease position and permit movement of the operator to actuatedposition.

3. A bidirectional sensor comprising, in combination, a support, anoperator mounted on the support for axial movement between unactuatedand actuated positions, means biasing the operator to actuated position,detent means surrounding the operator and movable axially thereofbetween detent and released positions with respect thereto and holdingthe operator against movement to actuated position in the detentposition thereof, a pair of seismic masses, means respectively mountingeach mass on the support for movement axially of the detent means, meansrespectively biasing the masses in opposite axial directions torespective first positions and resisting reverse axial movement thereofto respective second positions upon receipt thereby of an accelerationpulse of predetermined amplitude and time directed generally axiallythereof, and axially spaced shoulder means on each mass arranged inrespective pairs, one pair of shoulder means engaging the detent meansand locating the detent means in detent position in the first positionof the masses, one shoulder means of the other pair engaging means onthe detent means upon movement of the mass respective thereto to thesecond position thereof to move the detent means to released positionand permit movement of the operator to actuated position.

4. A bidirectional sensor comprising, in combination, a hollow tubularsupport, an operator slidably mounted within the support for movementbetween unactuated and actuated positions, means biasing the operator toactuated position, an annular detent member circumferentiallysurrounding the support and movable axially thereof between detent andreleased positions with respect to the operator, means coacting with thedetent member and operator and holding the operator against movement toactuated position in the detent position of the detent member, a pair ofseismic masses, means respectively mounting each mass on the support formovement axially of the support and the detent member, and meansrespectively biasing the masses in opposite axial directions torespective first positions and resisting reverse axial movement thereofto respective second positions upon receipt thereby of an accelerationpulse of predetermined amplitude and time directed generally linearlythereof, each mass including an axially spaced pair of shoulder means,one shoulder means of each pair engaging the detent member axially anddiametrically opposite of the other to locate the detent member indetent position in the first position of the masses, the other shouldermeans of one mass engaging the detent member upon movement of the onemass to the second position thereof to move the detent member out ofengagement with the one shoulder means of the other mass to releasedposition and permit movement of the operator to actuated position.

1. A bidirectional sensor comprising, in combination, a support, anoperator mounted on the support for movement between unactuated andactuated positions, means biasing the operator to actuated position,detent means movable between detent and released positions with respectto the operator and holding the operator against movement to actuatedposition in the detent position thereof, a pair of seismic masses, meansrespectively mounting each mass on the support for linear movementrelative to the detent means, means respectively biasing the masses inopposite linear directions to respective first positions and resistingreverse linear movement thereof to respective second positions uponreceipt thereby of an acceleration pulse of predetermined amplitude andtime directed generally linearly thereof, coacting means on each massand the detent means locating the detent means in detent position in thefirst position of the masses, and coacting means on each mass and thedetent means engageable with each other upon movement of either mass tothe second position thereof to move the detent means to releasedposition and permit movement of the operator to actuated position.
 2. Abidirectional sensor comprising, in combination, a support, an operatormounted on the support for axial movement between unactuated andactuated positions, means biasing the operator to actuated position,detent means movable axially of the operator between detent and releasedpositions with respect thereto and holding the operator against movementto actuated position in the detent position thereof, a pair of seismicmasses, means respectively mounting each mass on the support formovement axially of the detent means, means respectively biasing themasses in opposite axial directions to respective first positions andresisting reverse axial movement thereof to respective second positionsupon receipt thereby of an acceleration pulse of predetermined amplitudeand time directed generally axially thereof, coacting means on each massand the detent means locating the detent means in detent position in thefirst position of the masses, and second means on each mass spacedaxially of the first means and the detent means and engageable wiTh thedetent means upon movement of either mass to the second position thereofto move the detent means to released position and permit movement of theoperator to actuated position.
 3. A bidirectional sensor comprising, incombination, a support, an operator mounted on the support for axialmovement between unactuated and actuated positions, means biasing theoperator to actuated position, detent means surrounding the operator andmovable axially thereof between detent and released positions withrespect thereto and holding the operator against movement to actuatedposition in the detent position thereof, a pair of seismic masses, meansrespectively mounting each mass on the support for movement axially ofthe detent means, means respectively biasing the masses in oppositeaxial directions to respective first positions and resisting reverseaxial movement thereof to respective second positions upon receiptthereby of an acceleration pulse of predetermined amplitude and timedirected generally axially thereof, and axially spaced shoulder means oneach mass arranged in respective pairs, one pair of shoulder meansengaging the detent means and locating the detent means in detentposition in the first position of the masses, one shoulder means of theother pair engaging means on the detent means upon movement of the massrespective thereto to the second position thereof to move the detentmeans to released position and permit movement of the operator toactuated position.
 4. A bidirectional sensor comprising, in combination,a hollow tubular support, an operator slidably mounted within thesupport for movement between unactuated and actuated positions, meansbiasing the operator to actuated position, an annular detent membercircumferentially surrounding the support and movable axially thereofbetween detent and released positions with respect to the operator,means coacting with the detent member and operator and holding theoperator against movement to actuated position in the detent position ofthe detent member, a pair of seismic masses, means respectively mountingeach mass on the support for movement axially of the support and thedetent member, and means respectively biasing the masses in oppositeaxial directions to respective first positions and resisting reverseaxial movement thereof to respective second positions upon receiptthereby of an acceleration pulse of predetermined amplitude and timedirected generally linearly thereof, each mass including an axiallyspaced pair of shoulder means, one shoulder means of each pair engagingthe detent member axially and diametrically opposite of the other tolocate the detent member in detent position in the first position of themasses, the other shoulder means of one mass engaging the detent memberupon movement of the one mass to the second position thereof to move thedetent member out of engagement with the one shoulder means of the othermass to released position and permit movement of the operator toactuated position.